This invention relates to radar chaff packages and especially to the proper dispersal of chaff packages from a carrier vehicle traveling at supersonic speeds.
One method of dispersing radar chaff is from carrier rockets which travel at supersonic velocities. Cylindrical packages, or "muffins", each of which consist of a roughly cylindrical bundle of chaff fibers, are wrapped circumferentially with paper for handling purposes. The muffins are then placed in a cylindrical container and several containers are packed together to form a chaff warhead.
The rocket propels the warhead to supersonic velocity and, on fuze actuation, the warhead opens like a clam shell to deploy the individual muffins into the supersonic shock wave. However, the chaff become tangled or birdnested and are slow to blossom into a large radar-reflecting cloud.
To overcome this problem, another wearhead was developed. The chaff is placed in small, wedge-shaped, plastic containers. A number of the wedges are then placed in a phenolic fiberglass cylindrical shell with prima cord running along the center line. On fuze actuation, the prima cord blows the wedges through the shell. At the same time, the prima cord actuates a one-second pyrotechnic delay cartridge in each wedge, allowing the wedges to slow to subsonic-velocity before the delay cartridges actuate a small powder charge which disperses the chaff from the wedges. This technique vastly improved the bloom rate.
Recently, orders of improvement in the chaff bloom rate have been obtained from subsonic mortor-propelled chaff heads using small chaff muffins wrapped circumferentially with multiple windings of mylar plastic film. These mylar windings hold the chaff in place for handling and subsonic deployment. Additionally, the time required for unwrapping allows the muffins to deploy or distribute themselves in space before dispersing the chaff fibers. This gives many well-distributed bloom centers and results in a large, rapidly blooming cloud. No explosive charge need be used for chaff dispersal from the muffins.
While the circumferentially wrapped chaff muffins deploy well at subsonic speeds, they disintegrate immediately when subjected to supersonic air streams. This causes the chaff to clump at one spot in space and give a small, slow-blooming chaff cloud which is an undesirable condition.